Stroboscopic means for timing fuel injection



06f 3, 1957 A. DRElslN ETAL 3,344,563

STROBOSCOPIC MEANS FOR TIMING FUEL INJECTQION Filed June 3, 1964 @www United States Patent O 3,344,663 STROBOSCOPIC MEANS FOR TIMING FUEL INJECTION Alexander Dreisin, Olympia Fields, and John Terrell,

Tinley Park, Ill., assignors to Allis-Chalmers Manufacturing Company, Milwaukee, Wis.

Filed .lune 3, 1964, Ser. No. 372,270 4 Claims. (Cl. 73-119) This invention relates to a timing indicator for a fuel injection type internal combustion engine. Particularly it relates to a timing indicator for indicating the opening and closing of a fuel injection valve.

Some timing indicators for fuel injectors have means attached to the injector to follow the opening and closing of the injector and to turn on a light as the injector opens and closes. One of the problems of some prior art timing indicators is that it has been difficult to provide for a selective indication of either the time the injector opens or the time it closes. Both points are significant in testing fuel injecting apparatus and it is desirable to be able to easily select either point while using one indicating device.

In other prior art timing indicators, mechanical switches have been connected to open or close in response to the position of the injector. In these indicators the connections between the switch and the light can be reconnected or switched to turn on the light eitherV when the injector opens or closes. However, mechanical switching devices generally have several disadvantages including difficult adjustment.

The timing indicator of this invention uses a transducer that follows the position of a fuel injection valve and correspondingly modulates a power source to provide a generally rectangular waveform output. The direction of the voltage changes of the rectangular Wave form indicates the opening and closing of the fuel injection valve. Means are provided to produce a signal pulse in response to each of the voltage changes and additional means are provided to select the set of signal pulses, either the opening or closing pulses, for flashing an indicating light.

The objects of this invention are: to provide a new and improved stroboscopic timing indicator for fuel injection engines; to provide a timing indicator electrically responsive to the position of the fuel injection valve; and to provide a timing indicator having means for selecting the flashing of the timing light to occur either when the fuel injection valve opens or when it closes.

Other objects and advantages will appear from the following detailed description of an embodiment of this invention.

FIG. 1 is a schematic drawing of an embodiment of a timing indicator according to this invention, and includes the general wave forms occuring along the conductors; and

FIG. 2 is a drawing of an embodiment of a fuel injection assembly illustrating the application of this invention.

The fuel injector shown in FIG. 2 has a housing 10 that is attached to an engine head 11 by any known means, not shown; a reciprocating valve element 12 that is opened by fuel pressure acting in opposition to a biasing spring 9; and a threaded opening 13 at one end of housing 10. A transducer such as differential transformer 14, is provided. Differential transformer 14 has a magnetic core 20 connected to fuel injection valve element 12 through opening 13 by a shaft 15 to mechanically follow the reciprocating position of valve element 12.

Differential transformer 14 comprises a magnetic core 20, a primary winding 17 with input conductors 21a and 2lb, and two secondary windings 18 and 19 with output conductors 22a and 22b. Primary winding 17 is energized along conductors 21a `and 2lb from an alternating power source, such as an oscillator 23, shown in FIG. 1, that produces an output 21. Output 21 preferably has a frequency considerably higher than the frequency of movement of operating valveV element 12-for example, about 50,000 cycles per second.

The secondary windings are positioned on opposite sides of primary winding 1'7 to provide for varying the relative magnetic coupling between the secondary windings and the primary winding varies in response to the position of the core relative to the windings. Magnetic core 20 is positioned to provide equal magnetic coupling from the primary to each secondary winding when valve element 12 is in a closed position. The secondary windings are wound in series or parallel but in opposing directions so that essentially no output appears at conductors 22a `and 22b when valve element 12 is in a closed position. When valve element 12 is moved to an open position the increased coupling effect to one secondary winding produces current and an output 22 appears across conductors 22a :and 22b. Output 22 is a modulated form of oscillator output 21.

Means are provided to demodulate and, if necessary, amplify output 22 by a demodulator and amplifie-r circuit 24 that is connected to receive modulated output 22. Circuit 24 produces an output 25 that is essentially an envelope of modulated output 22. This envelope, which in this embodiment has substantially a rectangular or square wave form, changes from a lower or zero voltage, to a higher voltage when the injector is opened and from the higher to the lower voltage when the injector is closed. Therefore, the rising edge of the rectangular wave form indicates that the injection valve is opening and the falling edge of the wave form indicates that the injection valve is closing.

Circuit 24 may be a conventional circuit comprising a rectifier, a low pass filter, and an amplifier. The rectifier passes only the positive or negative portion of the modulated output and the low pass filter substantially eliminates the oscillator frequency from output 22 to transmit only the low frequency envelope as output 25.

A first differentiating circuit 27 is connected to receive output 25 and differentiates the wave form to produce an output 28. Differentiating circuit 27 may comprise a series combination of a capacitor and a resistor having a time constant that is short compared with the period of output 25 so that the capacitor charges rapidly at each voltage change in the envelope and produces a short exponentially decaying voltage across a resistor to provide output 28. As the polarities are shown in the drawing, differentiating circuit 27 produces a positive spike in rcsponse to the positive going edge of the square wave of output 2S when the injection valve opens) and it produces a negative spike in response to the negative going edge (when the injection valve closes).

A phase inverter 30 is shown connected to invert output 25 to produce output 32. A single stage common emitter transistor amplifier or equivalent vacuum tube circuit are examples of circuits that can be used to provide a suitable phase inverter.

A second differentiating circuit 35 receives inverted output 32 and produces an output 36 that is substantially identical to output 28 of first differentiating circuit 27 but is opposite in polarity.

Means, such as a switch 37, are provided to select either output 28 of first differentiating circuit 27 or output 36 of second differentiating circuit 35. Switch 37 is connected to energize a pulse amplifier 39 that responds to spikes of one polarity but not the other. Pulse amplifier 39 may comprise a vacuum tube or transistor amplifier that is biased to turn on momentarily Yin response to a spike of one polarity to produce pulses 40 that provide sufficient power to momentarily turn on a timing light 41.

Pulse amplifier 39 produces a short pulse, as output 40, when the injector opens or when the injector closes, depending on the position of switch 37. This output is connected to flashlight 41. The periodic ash can be used to illuminate a marker on a rotating part of the engine.

Alternate ways of connecting the differentiating circuits and phase inverter could be utilized. For example, a single differentiating circuit could be used to produce a pulse output (such as output 28) as output 25. A phase inverter could then be connected to invert output 28. The switching device would then connect the pulse arnplifier to receive either the output of the differentiating circuit or the output of the phase inverter. Depending on the position of the switch, the timing light would flash in response to either the opening or closing of injection valve 12.

In describing the invention, the preferred embodiment has been shown and described, but it is obvious to one skilled in the art that there are many variations, combinations, alterations, and modifications that may be made without departing from the spirit of the invention or from the scope of the appended claims.

The embodiments of the invention in which an eX- clusive property or prividege is claimed are defined as follows:

1. Means for producing a signal for selectively indicating the opening and closing of a fuel injection valve, said means comprising:

means for producing an oscillating output; a differential transformer having a primary winding, a secondary winding, and a movable magnetic core, said primary winding connected to receive the oscillating output as an input, and said core connected to move in response to movement of the injection valve and positioned within said transformer to vary the magnetic coupling between the primary winding and the secondary winding to produce a modulated output at the secondary winding having one voltage when the valve is closed and another voltage when the valve is open;

means connected to receive the transformer output and demodulating said modulated output to provide a demodulated output having voltage changes of one polarity corresponding to the opening of the valve and voltage changes of another polarity corresponding to the closing of the valve;

means for inverting the demodulated output;

differentiating means responsive to voltage changes of the one polarity to produce pulses;

stroboscopic means responsive to the pulses for producing a flashing light signal in response to the pulses; and

means for selectively connecting the differentiating means to receive the modulated output and the inverted modulated output.

2. Means for producing a signal for selectively indicating the opening and closing of a fuel injection valve, said means comprising:

means for producing an oscillating output;

a differential transformer having a primary winding, a secondary winding, and a movable magnetic core, said primary Winding connected to receive the oscillating output as an input, and said core connected to move in response to movement of the injection valve and positioned within said transformer to vary the magnetic coupling between the primary winding and the secondary winding to produce a modulated output at the Secondary winding having one voltage when the valve is closed and another voltage when the valve is open;

means connected to receive the transformer output for demodulating `said modulated output to provide a demodulated output having voltage changes of one polarity corresponding to the opening of the valve and voltage changes of another polarity corresponding to the closing of the valve;

means for inverting the demodulated output;

first and second differentiating means each responsive to voltage changes of the one polarity to produce first pulses of one polarity, said first differentiating means connected to receive the demodulated output as an input and said second differentiating means connected to receive the inverted demodulated output as an input;

stroboscopic means responsive to pulses of the one polarity for producing a ashing light signal in response to said pulses; and

means for selectively connecting the stroboscopic means to receive the first differentiating means pulses and the second differentiating means pulses.

3. Means for producing a signal for selectively indicating the opening and closing of a fuel injection valve, said means comprising:

means for producing an oscillating output;

a differential transformer having a primary winding, a secondary winding, and a movable magnetic core, said primary winding connected to receive the oscillating output as an input, and said core connected to move in response to movement of the injection valve and positioned within said transformer to vary the magnetic coupling between the primary winding and the secondary winding to produce a modulated output at the secondary winding having a lower voltage when the valve is closed and a higher voltage when the valve is open;

means connected to receive the transformer output for rectifying and demodulating said transformer output to provide an essentially square wave output having an increasing voltage corresponding to the opening of the valve and a decreasing voltage corresponding to the closing of the valve;

means for inverting the square wave output;

first and second differentiating means responsive to the increasing voltage to produce first pulses of one polarity and responsive to the decreasing voltage to produce second pulses of another polarity, said first differentiating means connected to receive the square wave output as an input and said second differentiating means connected to receive the inverted square wave output as an input;

stroboscopic means responsive to pulses of the one polarity for producing a ashing light signal in response to said pulses; and

means for selectively connecting the stroboscopic means to receive the first differentiating means pulses and the second differentiating means pulses.

4. Means for producing a signal for selectively indicating the opening and closing of a fuel injection valve, said means comprising:

means for producing an oscillating output;

a differential transformer having a primary winding, two secondary windings, and movable magnetic core, said primary winding connected to receive the oscillating output, said secondary winding positioned one on each side of the primary winding along lthe direction of movement of said core and said secondary windings connected together in electrical opposition to each other; and said core connected to move in response to movement of the injection valve and positioned within said transformer to couple the primary winding equally to the secondary windings when the valve is closed and to couple the primary winding unequally to the secondary windings when the valve is open;

means connected to receive the ouput of the secondary windings for rectifying and demodulating said output to provide an essentially square wave output having voltage changes of one polarity corresponding to the opening of the valve and voltage changes of another polarity corresponding to the closing of the valve;

means for inverting the square Wave output;

rst and second differentiating means each responsive to the voltage changes of one polarity to produce pulses of one polarity and each responsive to voltage changes of another polarity to produce pulses of another polarity, said rst differentiating means connected to receive the square wave output and said second differentiating means connected to receive the inverted square Wave output;

stroboscopic means respon-sive to pulses of the one polarity for producing a flashing light signal in re- 15 sponse to said pulses; and means for connecting the stroboscopic means to selectively receive the first differentiating means pulses and the second differentiating means pulses.

References Cited UNITED STATES PATENTS 2,601,447 6/1952 Neff 73-7l.4 X 2,691,888 10/1954 Daulby 73-116 3,119,258 1/1964 Taylor -73-119 3,247,710 4/ 1966 Thomas et al. 7371.4

FOREIGN PATENTS 729,431 5 195 5 Great Britain. 1,049,635 7/ 1959 Germany.

RICHARD C. QUEISSER, Primary Examiner. JAMES GILL, Examiner. JERRY W. MYRACLE, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CGRRECTION Patent No. 3,344,663 October 3, 1967 Alexander Dresin et al.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 45, for "and" read for Signed and sealed this 26th day of November 1968.

(SEAL) Attest:

Edward M. Fletcher, Jr. EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. MEANS FOR PRODUCING A SIGNAL FOR SELECTIVELY INDICATING THE OPENING AND CLOSING OF A FUEL INJECTION VALVE, SAID MEANS COMPRISING: MEANS FOR PRODUCING AN OSCILLATING OUPUT; A DIFFERENTIAL TRANSFORMER HAVING A PRIMARY WINDING, A SEC- 